The catecholamine 3,4-dihydroxyphenethylamine, or dopamine, acts as a neurotransmitter across a broad phylogenetic spectrum. Functions attributed to dopamine in the mammalian brain include regulation of motor circuits, valuation of sensory stimuli, and mediation of reward or reinforcement signals. Considerable evidence also supports a neurotransmitter role for dopamine in gastropod molluscs, and there is growing appreciation for its potential common functions across phylogeny. This article reviews evidence for dopamine’s transmitter role in the nervous systems of gastropods. The functional properties of identified dopaminergic neurons in well-characterized neural circuits suggest a hypothetical incremental sequence by which dopamine accumulated its diverse roles. The successive acquisition of dopamine functions is proposed in the context of gastropod feeding behavior: (1) sensation of potential nutrients, (2) activation of motor circuits, (3) selection of motor patterns from multifunctional circuits, (4) valuation of sensory stimuli with reference to internal state, (5) association of motor programs with their outcomes, and (6) coincidence detection between sensory stimuli and their consequences. At each stage of this sequence, it is proposed that existing functions of dopaminergic neurons favored their recruitment to fulfill additional information processing demands. Common functions of dopamine in other intensively studied groups, ranging from mammals and insects to nematodes, suggest an ancient origin for this progression.

中文翻译：

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多巴胺作为腹足类软体动物的多功能神经递质：进化假说


儿茶酚胺 3,4-二羟基苯乙胺（或多巴胺）在广泛的系统发育谱中充当神经递质。哺乳动物大脑中多巴胺的功能包括运动回路的调节、感觉刺激的评估以及奖励或强化信号的调节。大量证据也支持多巴胺在腹足类软体动物中的神经递质作用，并且人们越来越认识到它在整个系统发育中的潜在共同功能。本文回顾了多巴胺递质在腹足动物神经系统中的作用的证据。在已明确表征的神经回路中所鉴定的多巴胺能神经元的功能特性表明，多巴胺通过该假设的增量序列积累其不同的作用。多巴胺功能的连续获取是在腹足动物摄食行为的背景下提出的：（1）潜在营养的感觉，（2）运动回路的激活，（3）从多功能回路中选择运动模式，（4）感觉刺激的评估参考内部状态，（5）运动程序与其结果的关联，以及（6）感觉刺激与其后果之间的一致性检测。在该序列的每个阶段，多巴胺能神经元的现有功能有利于它们的募集以满足额外的信息处理需求。多巴胺在其他经过深入研究的群体（从哺乳动物、昆虫到线虫）中的常见功能表明，这一进程有一个古老的起源。